I dont get the 100 & 500 rule?

[bennyg70]

Ive checke dout my stats against the 100 rule to see how 1u drops my bg reading and its pretty close...

I usually work on it dropping me by 3mmol, but the 100 rules says 3.5mmol, which to be fair is probably nearer the truth.

However the 500 rule I really dont get, I assume this only works if you eat the same amount of carbs every single day, I eat near enough the same amount - 140 - 160g carbs a day. Howeer the rule for me says that i should be working to 1 u to 17 g carbs. Where i work to around 1 u to 10.

I dont understand the theory behind the 500 rule at all...?

 

[robert72]

Hands up - I've completely misunderstood the 500 rule

Doesn't work for those of us who reduce our carbs anyway.

 

[Klang180]

This link describes the rule quite well:

http://www.diabetesnet.com/diabetes-control/rules-control/carb-factors

As far as i can tell it has nothing to do with the amount of carbs you eat a day (within reason of course) but is rather 500 or 450 (the latter is now recommended) divided by your TDD. I just ran it for me and i come out at 16:1 ratio. This is probably my average as before breakfast i am 11.5:1, lunch more like 15:1 and dinner 20:1.

 

[noblehead]

There's another good explanation about the 500 rule here:

http://www.livestrong.com/article/44587 ... -diabetes/

 

[Klang180]

There's another good explanation about the 500 rule here:

http://www.livestrong.com/article/44587 ... -diabetes/

This article suggests it is based on your carb intake, my mistake, i had never read that elsewhere.

So from what i can tell you need to know how many carbs you eat in a day, how total units you take in a day and divide the first by the last. The problem is that if you are a rollercoaster or running high or low then you are either having too little/much insulin or too little/much carbs. So in essense it is a bit of a misleading guideline as it would only work well if you IC ratio was already set appropriately and then why would you need to know?

have i missed something?

 

[AMBrennan]

Random question... why does the 500 rule assume 500g carb intake (2000kcal alone) when GDA for carbohydrates is 200g/230g for women/men respectively. That seems... questionable at best.

Secondly, what's the point of it? Once you have adjusted the dose to get acceptable BG results (which you'll have to do anyway, as mentioned above), then divide the insulin by the amount of carbs isn't exactly rocket science. The livestrong article suggests that it's useful for those that don't carb-count, but in that case what's the point of knowing your ratio?

 

[phoenix]

I agree that it doesn't have anything to do with eating 500g of carbs , though Walsh eho devised it would be suggesting and presumably expecting an intake of 50-60% carbs. This wouldn't amount to 500 for most people.

This is the most detailed info I could find.

A variety of formulas that were at first empiric and later based on research conducted by single clinics have been proposed to derive pump doses from the TDD. Dr. Paul Davidson proposed the first formula for the CorrF in the mid 1980s. This straightforward formula, called the “1500 rule,” was based on his clinical experience with regular insulin among patients at his Atlanta clinic:

(1)

In 1994, Walsh and Roberts introduced a similar CarbF formula for multiple daily injections and insulin pumps.1 This “450 rule” was based on Walsh's clinical experience in San Diego with patients using regular insulin and paralleled the 1500 rule:

(2)

While accurate for average body weights and insulin sensitivity (IS), the 450 rule becomes less accurate with variations in body weight and IS. Modifications of the numerator in both formulas have been introduced over the years: 1800 and 2000 for the CorrF and 500 and 300 (for children) for the CarbF.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2956816/

 

[Klang180]

Oh well seen as no one is "average body weight" then it is fairly useless. Averages tell you nothing and so it does seem a little pointless.

I guess as a starting point it might be useful but it really is only the very foundation.

I eat between 300-400 carbs a day and most would consider that high so how anyone reaches 500 i don't know!

 

[bennyg70]

Surely everyones rule is going to be totally different... thats why it makes no sence, and if you can make it back fit, then you already know the information its trying to tell you anyway?

My rule considering i use 30 U insulin & i eat 150 carb a day is...... duh duh duh duuuuuuhhh

"the 300 rule" Trademark - Bennyg70

... Still dont think i get it.

 

[AMBrennan]

Oh well seen as no one is "average body weight" then it is fairly useless. Averages tell you nothing and so it does seem a little pointless.

They're useful as a starting point, and I don't think anyone would suggest otherwise.

 

[cdpm]

so if someone eats say
200 g carbs a day
couldn't they change that number
from 500 to a 200 (or whatever amount they eat0
and do the formula the same?

 

[TorqPenderloin]

so if someone eats say
200 g carbs a day
couldn't they change that number
from 500 to a 200 (or whatever amount they eat0
and do the formula the same?

No, the 500 is a constant meaning it will stay the same no matter what your carb intake is.

The 500 rule is for type 1 diabetics to measure their insulin:carb ratio. It actually has NOTHING to do with how many carbs you're consuming in a given day.

example: 500 (again this number never changes)/ 30 (total units of insulin injected per day)= 16.6grams of carbs per unit of insulin

While your question was answered several times in this thread, kudos for searching for information. I can appreciate that..

 

[LucySW]

No, the 500 is a constant meaning it will stay the same no matter what your carb intake is.

The 500 rule is for type 1 diabetics to measure their insulin:carb ratio. It actually has NOTHING to do with how many carbs you're consuming in a given day.

example: 500 (again this number never changes)/ 30 (total units of insulin injected per day)= 16.6grams of carbs per unit of insulin

While your question was answered several times in this thread, kudos for searching for information. I can appreciate that..

But I don't get this *at all*. I eat about 40g carbs a day and my TDD is 12.

So daily carb intake / TDD is c. 3.5. Which impressionistically is about right, because I have to bolus for protein too.

But 450/12 is 37.5. What would that indicate?

Lost. Lucy

 

[tim2000s]

@LucySW I'd suggest the key difference is that you are T1.5 and that your TDD suggests that you are still producing your own insulin to some extent. The first link posted states that the rule works best for those who are not producing insulin.

As has been mentioned, it is based on empirical observational data and is NOT based on the carb amounts consumed per day, even though some sites seem to persist with this fallacy.

I assume the CorrF calculation that @phoenix posted is intended for use in the US as the numbers come out screwy for mmol/l, but are fine for mg/dl, although they don't quite stack up right for what I get.,

 

[TorqPenderloin]

Tim is spot on (once again). The "formula" is for type 1 diabetics and assumes your pancreas is producing no insulin.

I put "formula" in quotes because it's pretty useless in all honesty, even for type 1 diabetics. Many people are overthinking the calculation and it's really not very scientific. The best thing it offers is a rough estimate of your carb ratio or how many units of insulin you should be taking (you need to know one or the other).

As a type 1 (or any diabetic for that matter) "Rough estimates" are useless. Im a perfect example as a type 1 diabetic still in the honeymoon phase. My extended release Levemir is working great for me, but Im extremely sensitive to my meal-time Humalog insulin. I have to measure in half units and follow a 30:1 carb:insulin ratio. 1 unit of Humalog without food will easily drop my blood sugar 100 points (mg/dl).

Im currently taking 30-32 total units of insulin a day. According to the 500 Rule that means my carb ratio is around 16:1 which is nearly half what is working well (30:1) for me. Following a 16:1 ratio would be a great way to kill myself (which I'd prefer not to do).

Side note: the 500 rule also fails to consider activity levels which is one of the reasons the calculation is so off for me.

Bottom line: you may talk to your doctor about the 500 Rule, but in my opinion it's nothing short of useless.